Re:: Dose rate constants -Reply

[FRAMEP@ORAU.GOV]

Joel:
     >Boy, I hope that I don't get too pounded for this one,

Gee, was I that nasty. I guess I need to take a kinder, gentler
approach. My apologies.     

 >    As  most,  if  not  all  of you know, when  you  look  at  a
>full/detailed  decay  scheme  of  many  radioisotopes,  including
>I-125, there is a LOT going on (i.e. x-rays as well).
>The  original  Radiological Health Handbook (last  published
>Jan.  1970)  gives a "Gamma" constant for I-125 at  approximately
>.07  R/hr at 1m/Ci.  This may be a true number for the gammas and
>only the gammas and may not include the plethora of x-rays...

I'm not sure either, the RHH got their numbers from Jaeger but Jaeger
got his from several sources,  mostly the old Amersham Radiochemical
Manual which I don't have. 

>However,  I am so used to taking the information in the "old
>book"  as tried and true, that I find it hard to put credence  in
>the  younger  come-up-en's numbers... I'd sure like to  see  some
>real  experimental  evidence  on this and other  gamma  constants
>(excuse me, dose rate constants).
> Joel Baumbaugh, RSO
 
Might I be permitted to express the opinion that the old rad health
handbook, that book of wisdom and fountain of knowledge, is full of
land mines. For example, p 131, where the gamma constants are listed,
carries the title "Gamma Radiation Levels for One Curie of Some
Radionuclides"  WRONG. They give the values for  millicurie sources,
not curie sources. Other mistakes that I've run across include
reporting the U-235 specific activity and half life as those of
U-234, and the specific activity and half life of U-238 as that of
U-235 (some versions don't make the latter mistake) on p 104. The
reported half life of Ba-133 is listed as 7.2 years when in fact its
over ten. These RHH errors have propogated themselves. Old Ba-133
check sources with the half life specified often used the RHH number
and the last time I looked at the DOT regs (49 CFR 71 App A), they
used the RHH specific activity for Ba-133 of 374 Ci/g and rounded it
up to 400 when in fact it should be 255.

I would strongly recommend avoiding the old RHH except when
necessary.

Enjoy the good weather in CA. We've got snow in Tennessee.

Best wishes

Paul Frame